The releases are the latest in the ongoing Sorghum Conversion Program, in which breeders convert tropical sorghums into varieties that will grow in temperate areas.

The converted lines can be harvested by combines, because they are several feet shorter than tropical sorghums.

In many parts of the world, sorghum is grown as a food crop. In the United States, however, the grain is used primarily as livestock feed and vegetative parts are made into hay and silage. In 1995, 8.2 million acres of sorghum were grown in the United States with an estimated farm value of more than $1 billion.

The key to the Sorghum Conversion Program is classical plant breeding, which changes the plants genetic internal clock. The tropical plants are used to shorter days and warmer climates along the equator. So, scientists cross these with plants from temperate areas, creating lines that thrive during the longer days of spring and summer in temperate zones farther from the equator.

The latest group of 40 sorghums come from 13 different countries. Seed from the new lines is available to breeders.